29. If 4x² + y = 40 and xy = 6, find the value of 2x + y and 2x – y

1.	29. If 4x² + y = 40 and xy = 6, find the value of 2x + y and 2x – y.
Answer» Answer: Hi, We KNOW that, __________________ ( a + B )² = a² + 2ab + b² ___________________ According to the problem given, 4x² + y² = 40-------( 1 ) xy = 6----------------( 2 ) Do the square of ( 2X + y ), ( 2x + y )² = ( 2x )² + 2 × 2x×y + y² = 4x² + 4xy + y² = 4x² + y² + 4xy = 40 + 4 × 6 [ from ( 1 ) and ( 2 ) ] ( 2x + y )² = 40 + 24 = 64 Therefore , 2x + y = ±√64 = ± 8 I hope this helps you. :)

29. If 4x² + y = 40 and xy = 6, find the value of 2x + y and 2x – y.

Answer»

Answer:

Hi,

We KNOW that,

__________________

( a + B )² = a² + 2ab + b²

___________________

According to the problem given,

4x² + y² = 40-------( 1 )

xy = 6----------------( 2 )

Do the square of ( 2X + y ),

( 2x + y )² = ( 2x )² + 2 × 2x×y + y²

= 4x² + 4xy + y²

= 4x² + y² + 4xy

= 40 + 4 × 6

[ from ( 1 ) and ( 2 ) ]

( 2x + y )² = 40 + 24

= 64

Therefore ,

2x + y = ±√64

= ± 8

I hope this helps you.